The present invention relates to a process for producing a 2-adamantyl (meth)acrylate of the formula (I) 
wherein R1 is hydrogen or methyl and R2 is hydrogen of lower alkyl.
JP-A-9-73173 discloses that the 2-adamantyl (meth)acrylate of the formula (I), especially a compound having alkyl as R2, is useful as a raw material of chemical amplification resist. Such a 2-adamantyl (meth)acrylate is commonly produced by reacting a corresponding (meth)acryloyl halide and a corresponding 2-adamantanol. Since a product obtained by such a reaction contains much impurities and the crude product are often colored, purification treatment is generally conducted after the reaction. For example, when the above reaction is carried out in an organic solvent, the resulting reaction mixture is generally subjected to a post-treatment such as washing with water, the solvent is generally evaporated off, and column purification or distillation is generally conducted.
Further, a method wherein a (meth)acryloyl halide and a 2-adamantanone, both of which correspond to the above formula (I), are reacted has also been known. JP-A-10-182552 discloses a method wherein the reaction of the acid halide and the ketone is carried out in the presence of a specific Grignard reagent or organolithium compound. In such a reaction of the acid halide and the ketone, a product contains much impurities. Therefore, in the Examples in the publication, after the reaction is conducted in an organic solvent, the crude product obtained by concentration is subjected to column purification.
However, the column purification is not always efficient from a treatment capacity consideration. For example, the column purification using a silica gel column requires a large amount of silica gel (packing) as much as about 30 times by weight with respect to a substrate to be purified, and it takes much time to pass a solution to be purified through the column. In addition, purification by distillation require special conditions such as addition of stabilizers and high vacuum because of insufficient thermal stability of the 2-adamantyl (meth)acrylate to be purified. Therefore, it is difficult to apply column purification and distillation particularly for the purification of the above 2-adamantyl (meth)acrylate in an industrial scale. Further, it is also difficult to carry out the aforementioned method disclosed in JP-A-10-182552 in an industrial scale because the Grignard reagent or organolithium compound is expensive or requires careful handling and column purification is also necessary.
The present inventors have studied intensively to produce a purified product of the 2-adamantyl (meth)acrylate of the formula (I) by a method which can be carried out easily even in an industrial scale. As a result, they have found that a 2-adamantyl (meth)acrylate of high quality can be produced very efficiently by adsorbing and removing impurities formed in the reaction of a (meth)acryloyl halide and a 2-adamantanol with active carbon. The present invention was thus accomplished.
The present invention provides a process for producing a 2-adamantyl (meth)acrylate of the formula (I): 
wherein R1 is hydrogen or methyl and R2 is hydrogen of lower alkyl, which comprises reacting a (meth)acryloyl halide of the formula (II): 
wherein R1 is as defined above and X is halogen with a 2-adamantanol of the formula (III): 
wherein R2 is as defined above to form the 2-adamantyl (meth)acrylate of the formula (I), then treating a solution of this product in an organic solvent with active carbon, subsequently removing the active carbon, and thereafter separating a purified 2-adamantyl (meth)acrylate.